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coverage: Remove enum CoverageStatement
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This enum was mainly needed to track the precise origin of a span in MIR, for
debug printing purposes. Since the old debug code was removed in rust-lang#115962, we
can replace it with just the span itself.
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Zalathar committed Oct 8, 2023
1 parent de2f0d5 commit dcc71a6
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Showing 2 changed files with 17 additions and 46 deletions.
51 changes: 15 additions & 36 deletions compiler/rustc_mir_transform/src/coverage/spans.rs
Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,7 @@ use std::cell::OnceCell;

use rustc_data_structures::graph::WithNumNodes;
use rustc_index::IndexVec;
use rustc_middle::mir::{self, AggregateKind, BasicBlock, Rvalue, Statement, StatementKind};
use rustc_middle::mir::{self, AggregateKind, Rvalue, Statement, StatementKind};
use rustc_span::{BytePos, ExpnKind, MacroKind, Span, Symbol};

use super::graph::{BasicCoverageBlock, CoverageGraph, START_BCB};
Expand Down Expand Up @@ -51,27 +51,13 @@ impl CoverageSpans {
}
}

#[derive(Debug, Copy, Clone)]
pub(super) enum CoverageStatement {
Statement(BasicBlock, Span, usize),
Terminator(BasicBlock, Span),
}

impl CoverageStatement {
pub fn span(&self) -> Span {
match self {
Self::Statement(_, span, _) | Self::Terminator(_, span) => *span,
}
}
}

/// A BCB is deconstructed into one or more `Span`s. Each `Span` maps to a `CoverageSpan` that
/// references the originating BCB and one or more MIR `Statement`s and/or `Terminator`s.
/// Initially, the `Span`s come from the `Statement`s and `Terminator`s, but subsequent
/// transforms can combine adjacent `Span`s and `CoverageSpan` from the same BCB, merging the
/// `CoverageStatement` vectors, and the `Span`s to cover the extent of the combined `Span`s.
/// `merged_spans` vectors, and the `Span`s to cover the extent of the combined `Span`s.
///
/// Note: A `CoverageStatement` merged into another CoverageSpan may come from a `BasicBlock` that
/// Note: A span merged into another CoverageSpan may come from a `BasicBlock` that
/// is not part of the `CoverageSpan` bcb if the statement was included because it's `Span` matches
/// or is subsumed by the `Span` associated with this `CoverageSpan`, and it's `BasicBlock`
/// `dominates()` the `BasicBlock`s in this `CoverageSpan`.
Expand All @@ -81,7 +67,9 @@ struct CoverageSpan {
pub expn_span: Span,
pub current_macro_or_none: OnceCell<Option<Symbol>>,
pub bcb: BasicCoverageBlock,
pub coverage_statements: Vec<CoverageStatement>,
/// List of all the original spans from MIR that have been merged into this
/// span. Mainly used to precisely skip over gaps when truncating a span.
pub merged_spans: Vec<Span>,
pub is_closure: bool,
}

Expand All @@ -92,7 +80,7 @@ impl CoverageSpan {
expn_span: fn_sig_span,
current_macro_or_none: Default::default(),
bcb: START_BCB,
coverage_statements: vec![],
merged_spans: vec![],
is_closure: false,
}
}
Expand All @@ -102,8 +90,6 @@ impl CoverageSpan {
span: Span,
expn_span: Span,
bcb: BasicCoverageBlock,
bb: BasicBlock,
stmt_index: usize,
) -> Self {
let is_closure = match statement.kind {
StatementKind::Assign(box (_, Rvalue::Aggregate(box ref kind, _))) => {
Expand All @@ -117,39 +103,32 @@ impl CoverageSpan {
expn_span,
current_macro_or_none: Default::default(),
bcb,
coverage_statements: vec![CoverageStatement::Statement(bb, span, stmt_index)],
merged_spans: vec![span],
is_closure,
}
}

pub fn for_terminator(
span: Span,
expn_span: Span,
bcb: BasicCoverageBlock,
bb: BasicBlock,
) -> Self {
pub fn for_terminator(span: Span, expn_span: Span, bcb: BasicCoverageBlock) -> Self {
Self {
span,
expn_span,
current_macro_or_none: Default::default(),
bcb,
coverage_statements: vec![CoverageStatement::Terminator(bb, span)],
merged_spans: vec![span],
is_closure: false,
}
}

pub fn merge_from(&mut self, mut other: CoverageSpan) {
debug_assert!(self.is_mergeable(&other));
self.span = self.span.to(other.span);
self.coverage_statements.append(&mut other.coverage_statements);
self.merged_spans.append(&mut other.merged_spans);
}

pub fn cutoff_statements_at(&mut self, cutoff_pos: BytePos) {
self.coverage_statements.retain(|covstmt| covstmt.span().hi() <= cutoff_pos);
if let Some(highest_covstmt) =
self.coverage_statements.iter().max_by_key(|covstmt| covstmt.span().hi())
{
self.span = self.span.with_hi(highest_covstmt.span().hi());
self.merged_spans.retain(|span| span.hi() <= cutoff_pos);
if let Some(max_hi) = self.merged_spans.iter().map(|span| span.hi()).max() {
self.span = self.span.with_hi(max_hi);
}
}

Expand Down Expand Up @@ -673,7 +652,7 @@ impl<'a> CoverageSpansGenerator<'a> {
if self.pending_dups.is_empty() {
let curr_span = self.curr().span;
self.prev_mut().cutoff_statements_at(curr_span.lo());
if self.prev().coverage_statements.is_empty() {
if self.prev().merged_spans.is_empty() {
debug!(" ... no non-overlapping statements to add");
} else {
debug!(" ... adding modified prev={:?}", self.prev());
Expand Down
12 changes: 2 additions & 10 deletions compiler/rustc_mir_transform/src/coverage/spans/from_mir.rs
Original file line number Diff line number Diff line change
Expand Up @@ -63,26 +63,18 @@ fn bcb_to_initial_coverage_spans(
let data = &mir_body[bb];
data.statements
.iter()
.enumerate()
.filter_map(move |(index, statement)| {
.filter_map(move |statement| {
filtered_statement_span(statement).map(|span| {
CoverageSpan::for_statement(
statement,
function_source_span(span, body_span),
span,
bcb,
bb,
index,
)
})
})
.chain(filtered_terminator_span(data.terminator()).map(|span| {
CoverageSpan::for_terminator(
function_source_span(span, body_span),
span,
bcb,
bb,
)
CoverageSpan::for_terminator(function_source_span(span, body_span), span, bcb)
}))
})
.collect()
Expand Down

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